At 8:45 PM -0700 11/3/10, Peter Schmitz wrote:

I have a program (test.hs):

...

module Main (main) where import System.Exit main :: IO ExitCode main = do return (ExitFailure 1)

In another program, I invoke it via 'system':

...

exitCode <- system ".\\test.exe" case (exitCode) of ExitFailure failCnt -> do putStrLn $ "-- Fail count is: " ++ show failCnt exitFailure ExitSuccess -> do putStrLn $ "-- OK." exitSuccess

but it always gets ExitSuccess (not ExitFailure failCnt as I expected). (I am running under Windows.)

My other use of system (such as with ghc commands) works okay, sometimes getting success, sometimes failure, as expected.

Any suggestions much appreciated. Thanks, -- Peter

The value returned by `main` is always discarded. You need to use `exitWith`: main = exitWith (ExitFailure 1)